Means for roasting coffee or the like



1945- w. R. GOLDFTINE ,3 ,49

MEANS FOR RDA STING COFFEE OR THE LIKE Original Filed Jan. 2, 1941 5 Sheets-Sheet l fl- 5- w. GO LDFINE J 2,381,493

MEANS FOR ROASTING COFFEE OR THE LIKE OriginaLFiled Jan. 2, 1941 a Sheets-Sheet. 2

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w. R. cao| |:n =||\uz MEANS FOR ROASTING COFFEE OR THELIKE Original File d Jan. 2, 1941 3 Sheets-Sheet 3 to the beans in a uniform manner.

separate endless circuits or paths.

Patented Aug. 7, 1945 I MEANS FORROASTINGCOFFEE on THE LIKE I 'Wesley R. Goldfine, Chicago, 111., assignor to Airoast Corporation, Chicago, 111., a corporation of Delaware Original application January 2, 1941, Serial No. 372,710, now Patent No. 2,348,066, dated May 2, 1944. Divided and this application February 18,1943, Serial No. 476,281

1 Claim.

- This is a division of my'copending application,

I Serial No. 372,710, filed January 2, 1941, now Pat- .ent.No.- 2,348,066, of May 2, 1944, and relates particularly to improvements in an apparatus for roasting coffee or the like, and refers particularly to a means for roasting bean-like materialsquickg and uniformly with a minimum expenditure of One of the most troublesom factors encountered in roasting coffee or other bean-like materialsresides inthe difficulty of applying the-heat Apparatus heretofore proposed are predisposed to cause local overheating or local overroasting of the individual beans while other parts of the bean are underroasted. This is due in some measure to the fact that in most roasting apparatus the beans comeinto contact with relatively: hot surfaces and unless extreme care is exercised by an experienced operator, spotting or local overroasting of the beans results. In other cases the heat interchange relationship of the individual beans and the source of heat is such that uniform roastin is substantially i-mpossible' In View of the delicate flavor characteristicsof .beans such as coffee, a few spotted beans may serve to ruin the flavor of theentire roast. Under any circumstances non-uniformly roasted beans are not possessed of desired flavor characteristics and are not acceptable to the purchaser.

In the present invention, means are provided whereby the beans to be roasted are physically carried bya relativelyhot gas, usually heated air, moving at a comparatively high velocity, the

roasting zone comprising a common portion of the path-of travel of the beans andthe gas, both of which, outside of said common path, travel in The beans thus carried by-the high velocity hot gases are continuously in motion during the roasting period,

in an endless path, the gases being recirculated through an external circuit to replenish the heat zone. The beans, however, have been confined in a cage or screened compartment through which the heated air'passes, and do not pass through a :cycle of movement of their own. The result is thatthe beans are insuff ciently agitated to uniformly roast the same; the confining screen orv cage quickly becomes cloggedwithhulls and chaff; and due to the density of the mass of the beans in the cage andthe clogged screens, free circulation of the heated air is prevented resulting in local overroasting-of a portion of the beans and insufli-' cient roasting of other portions'thereof, and necessitating the use ofa blower of excessively'high capacity and poor control of the air temperature.

In the present invention, an of the beans in the roast move at a speed substantially equal to that of the heated air; resistance to all movement of the air is materially reduced; and no screens-are Other objects of the present invention will be 1 apparent from the accompanying drawings and following detailed description. 1 s

In the drawings, 4

Fig. "1 is a side elevational view, parts being broken away'and parts being shown in section, of

my improved device.

Fig. 2 is a rear elevational View, parts being shown in section, of the device'illustrated in Fig. '1.

Fig. 3 is a sectional view taken-on the line 33 of Fig. 5, illustrating the air inlet to the roastin chamber.

Fig. 4 taken online 4-4 of Fig. 2.

Fig. 5 is a sectional view taken on line 55'of Fig. 1, illustrating the interior of the roasting chamber. 7

Fig. 6 is a sectional view taken-on the line 66 of Fig; 2. 1

Referring in detail to the drawings, 1 indicates aroasting chamber'for coifee'beans or other beanlike material. The outlet 3 of 'a'blower Zccnnects into chamber I by means of a conduit 4 whereby air or o'thergas may be discharged at relatively .high velocity into the roasting chamber. The blower '2 is driven by motor 5 or other suitable prime mover. A conduit 6 connects the roasting chamber to the inlet -6' of blower 2, an electric heating unit 1, having electric connections 8, being positioned in'said conduit to heat the air or gas passing from thechamber I to the-blower 2.

The chamber I is provided with front and rear walls 9 and I'll, respectively, the lateral or connecting walls I'l being curvilinear in contour and defining therewith a closed compartment. Of course, it is not essential that'the outer surfaces of the walls H be curvilinear since no function is accomplishedthereby, but the inner contour must be curvilinear to provide the desired path for the passage of the beans and hot gases through the roasting zone, as will be hereinafter more fully described.

A conduit I2 is mounted upon the front wall 9, the interior of said conduit connecting into the upper portion of the roasting compartment through opening 13 provided in the wall 9. The upper portion of the conduit l2 may be connected with a closed hopper (not shown) whereby coffee beans or other bean-like material may be charged to the roasting chamber. A discharge opening I4 is provided in the wall I l at th bottom of the roasting chamber, said opening being controlled by butterfly valve whereby the roasted beans may be removed from the roasting chamher. A discharge conduit l6 directs the discharging beans to a hopper, bag or the like (not shown). During the roasting operation the valve i5 is swung to closed position.

i The interior of the compartment l is divided by a baffle l! which extends from wall 9 to wall Hi. One side of the baiiie ll is curved, as at I8 to conform with the contour of the inner surface of wall ll. Thusa zone or compartment I9 is provided which extends from the inlet 4 to the upper end of the curved portion of the bafii H. The A gas inlet to the compartment comprises a substantially rectangular opening 29 which causes the air or gas discharged from the blower Z to enter the roasting zone along a tangent to the curved wall II. The zone I9 is of comparatively restricted cross-sectional area and said area is substantially uniform up to the upper end of the baffle I1 whereby the air discharged through the opening travels through the zone 19 at a relatively high, substantially constant velocity.

The beans which have been deposited through the opening [3 ultimately find their way to a position in front of the opening 23 and when the hot air or gases are passed into the roasting zone said beans are bodily carried by the high velocity stream through the curved compartment l9. During this phase of theroasting period the beans are actually floating upon the rapidly moving gas stream and the individual beans are entirely surrounded by the hot gases and are hence uniformly roasted on all sides simultaneously. In view of the fact that the beans move rapidly through the zone l9, they never contact any solid surface for sufficient length of time to permit local overroasting or spotting. beans being washed by the rapidly moving current of air have the corona of gas or air, which normally surrounds each bean, removed. This permits more efiicient heating of the beans since said corona layer normally serves as an insulating medium upon the surface of the bean against the heating of the bean by convection heat.

As the beans, carried by the rapidly moving air stream pass the upper end of the baffle H, the roasting chamber widens out thereby reducing the velocity of travel of the air to such an extent as to permit gravity to pull the beans downwardly. The beans thus left in an unsupported manner fall to the bottom of the roasting compartment where they are again caught by the incoming stream of hot air and the cycle is repeated.

A second bafiie 2| extends from the upper portion of the wall II and is so curved as to direct the beans projected from the zone 19 in a downwardly direction toward the gas inlet opening 26. The bafiie 2|, in addition functions in a manner similar to a jetty causing a diminution in the velocity of the traveling air and permitting said air to swirl or eddy around the back of the baiile while dropping the beans from entrainment. A

As a further advantage, the

gas discharge opening 22 is provided behind the baffle 2| whereby the air is drawn into the conduit 6 wherein its lost-heat is replenished prior to again returning to the roasting compartment.

In practice it has been found that there are essentially two air streams circulating in the roasting chamber. The first air stream comprises that air which enters the chamber through the opening 20. It is this stream which primarily carries the beans through the chamber, the bulk of the stream traversing the outer defining periphery of the chamber. A portion of this stream, after expansion takes place in the chamber, leaves the chamber through the exit 22. Another portion of this stream, after expansion takes place in the chamber, is induced, by the injector action of the main stream entering the chamber through the opening 20, downwardly toward said opening and is recirculated in a substantially parallel relationship with the stream entering the chamber through the opening 28. However, the induced stream follows the contour of the baffle ll.

The induced stream is helpful in theprccess in that it serves as a cushion when the beans, at the upper portion of their travel in the chamber, fall from the stream carrying them. This fact permits relatively high air velocities to be used without serious danger of breaking or cracking the beans by impact with any solid surface.

Because of the rapid and eficient heat interchange between the beans and the circulating air, lower roasting temperatures can be employed than have heretofore been possible. For example, 18 ounces of green coffee were roasted at 470 R, in a period of 3 minutes. During the roasting operation cubic feet per minute of heated air was in circulation in the roasting chamber and it was found that the entire mass of beans circulated 3600 times per minute around the bafile ll. The efficiency and uniformity of heat interchange can bejudg'ed by the rate at which it is possible to circulate the beans in the roasting chamber. In addition, it has been estimated that there is an average of about three revolutions of each bean about its own axis for each cycle through the roasting chamber.

Of course, the present invention is not to be limited by the above example, since it is merely set forth for purposes of illustration.

It has been found, however, that in the present process, roasting temperatures for coffee ranging between about 430 and 475 F., are suitable. Of course, the quantity of heated air introduced per unit of time, the velocity of the air delivered by the blower, or the quantity of air in circulation in the roasting chamber at any predetermined time, will depend largely upon the number of beans, that is, the amount of bean-like material to be kept in circulation and the size of the unit. For a roasting unit of predetermined size, uniform roasting is difiicult of attainment at below about 40 per cent of its rated or maximum capacity. For example, for a unit of 18 /2 ounces capacity, satisfactory uniform roasting can be obtained when more than about 8 ounces of coffee is being roasted, Below about 8 ounces uniform roasting is difficult of attainment.

The lower velocity limit, in general, is that velocity or that quantity of air which is in circulation at a predetermined time which will maintain all of the beans in circulation, and the upper limit of velocity will be determined principally upon considerations of breaking or cracking the beans when higher velocities are employed, In addition, excessive air velocities are likely to cause tion of about 2 or 3 per cent can be employed,

above or below the quantity of air in circulation, as hereinbefore described for a predetermined weight of cofiee without encountering diificulties,

In general, as the capacity of the unit increases,

the quantity of air in circulation or air velocity for a predeterminedweight of coffee' increases.

The apparatus comprising the present invention is shown in its essential form and obvious associated equipment such as insulation surrounding the compartments and conduits through which the hot gases are circulated is contemplated. Of course, the size of the motor and blower must be such, depending upon the size of the roasting compartment, conduits, etc., and the, individual and total weight of the beans to be roasted, that the beans can be carried in entrainment in the zone l9. In addition, the heat capacity of the heating unit 1 will, of course, depend I upon the velocity and total volume of air to be heated and the rate at which it is desired to carry out the roasting operation.

The roasting machine may be constructed as a unit, having a main supporting frame ,23 upon which the roasting chamber I may be mounted. An auxiliary frame 24 maybe carried by frame 32 and 33, interposed between which are a plurality of angularly spaced radial vanes 34. A closure 35 is provided for the housing 30 which may be removably secured to the housing.

I claim as my invention:

In a device of the character described, a housing having side walls and a curvilinear outer wall disposed about a horizontal axis, a substantially segment shaped bailie extending transversely between said side walls and having its arcuate portion disposed in spaced relation to the adjacent portion of said curvilinear wall to define therewith a substantially uniform area passageway extending across thebottom of the housing and thence upwardly to terminate approximately midway between the bottom and top of the housing,

the flat portion of said segment shaped baiile being inclined at an angle of approximately 30 shaped bafile to direct a flat stream of air through 23 and may, in turn, support the motor 5. Shaft 25 of motor 5 carries a pulley 26 over which a belt 2'! travels, said belt also being trained around pulley 28, which, in turn, is carried by shaft 29 of blower 2. The blower I comprises a housing '30 withing which a rotor 3| is eccentrically positioned, the rotor comprising a pairof spaced discs from a horizontal plane, 'said housing having anelongated horizontally disposed air inlet opening disposed below the lower end of said segment said passageway and along the inner side of said curvilinear outer wall, the side wall of said housing having a material charging inlet disposed above the inclined fiat surface of said bafile, said housing having a material discharge passageleading from the lower portion of said curvilinear Wall, valve means disposed in said material discharge passage and having its upper side conforming to the contour, of said curvilinear outer wall, an arcuate partition forming part ,of and extending downwardly from the upper portion of said curvilinear wall and terminating in spaced relation to the lower end of said segment shaped baffle, side wall of said housing having a hot air outlet disposed at its upper end on the opposite WESLEY R. GOLDFINE. 

